Dr. Taegtmeyer's group continues to examine mobilization of glycogen and glycogen turnover during normoxia and myocardial ischemia. The goal is to use 13C NMR isotopomer analysis to monitor the contribution of glycogen to acetyl-CoA and energy generation. The basic protocol uses depletion followed by glycogen repletion with 13C enriched glycosyl units. Tissue extracts from experiments performed in Houston were analyzed at the Resource and demonstrated that lactate, glutamate and glucose could be easily detected. However, with the very brief (3 min) period for citric acid cycle turnover plus the low enrichment inherent in the use of [1-13C] glucose, 13C-13C spin-spin coupling could not be detected. These experiments were redesigned with [1,6-13C] glucose and a longer period for cycle turnover which should yield spectra suitable for analysis. (Collaborative 7) REPORT PERIOD: (09/01/97-08/31/98)